1. Field of the Invention
The present invention relates to a method of decomposing pollutants such as gaseous halogenated aliphatic compounds and an apparatus for use in the method.
2. Related Background Art
An enormous amount of halogenated aliphatic hydrocarbon compounds (e.g. chlorinated ethylene, chlorinated methane) have been used in association with recent advancement of industrial technologies, and the disposal of these compounds has become a serious problem. Also, environmental problems of natural environment being polluted with gases from these compounds after use, and so on, have been caused, and considerable efforts have been expended in solving those problems.
As an example of apparatuses to contribute to the solution of the problems as described above, apparatuses for decomposing gaseous halogenated aliphatic hydrocarbon compounds in which a gas containing a chlorine gas is mixed with a gaseous halogenated aliphatic hydrocarbon compound to be decomposed, and the mixed gas is irradiated with light have been proposed (for example, Europe Patent Publication EP100453A1). Here, as simple and safe means for obtaining a gas containing a chlorine gas, a chlorine gas generated from a solution containing chlorine is used.
FIG. 1 is a schematic diagram of one aspect thereof, wherein reference numeral 11 denotes means for generating air containing a chlorine gas, which comprises a water bath 12 containing a chlorine solution, a pipe 13 for passing air through the solution, and a valve 14 to adjust the amount of air. And, the air passed through the chlorine solution becomes air containing a chlorine gas, and is introduced into a reaction baths 5. Reference numeral 1 denotes an apparatus for supplying a gas to be decomposed, and the gas to be decomposed is introduced into the reaction bath 5, and is mixed with the air containing a chlorine gas in the reaction bath 5, and the mixed gas is irradiated with light for a predetermined time period by light-irradiating means 4, whereby the gas to be decomposed is decomposed. The decomposed gas is discharged from an exhaust pipe 6.
For the chlorine solution that is put in the water bath 12, a solution with the concentration of hydrogen ions (pH value) being in the range of from 1 to 4 and the concentration of chlorine being in the range of from 5 to 150 mg/l, or the like, is used. Such a solution can be obtained by dissolving a hypochlorite (sodium hypochlorite and potassium hypochlorite) in water, for example. Also, chlorine gas can be generated efficiently if an inorganic acid or the like is contained in this solution.
Also, a pair of electrodes is put in water containing an electrolyte, and an electric potential is applied therebetween, whereby a solution having the above described properties can be produced near the positive electrode. The water produced by such electrolysis is called electrolytic water, functional water or the like, and apparatuses for producing such water are commercially available for use in disinfections and the like. As shown in FIG. 2, functional water at a positive electrode 23 by a functional water production apparatus 21 constituted by an electrolytic device 22 is continuously supplied at a desired flow rate to the chlorine gas generation bath 11 through a pump 25 and a pipe 26. In this figure, reference numeral 24 denotes a negative electrode, and reference numeral 27 denotes a partition wall for separating the positive electrode side from the negative electrode side. A gas to be passed is continuously supplied at a desired flow rate to the chlorine gas generation bath 11 through a supply pipe 13 and a pump 14. As a result, a gas containing chlorine gas is discharged from an outlet pipe 3 . This gas containing chlorine is introduced into the reaction bath 5, and thereafter the compound to be decomposed is decomposed in a way as described above. Also, functional water used in this processing is discharged from the chlorine generation bath 11 to a tank 8. For a method in which air is passed through a chlorine solution to generate air containing chlorine gas in this way, it is not necessary to prepare a chlorine container or the like, chlorine can be supplied safely, conveniently and stably.
However, in the above mentioned apparatus for decomposing gaseous halogenated aliphatic hydrocarbon compounds, a chlorine gas supplied from water or the like containing chlorine is mixed with a gaseous halogenated aliphatic hydrocarbon compound as a decomposition target substance under irradiation with light, thereby carrying out decomposition reaction, and in particular pollutant gases are purged. In this apparatus, if a configuration in which the decomposition target substance is first introduced into the reaction vessel, and the substance is discharged without being decomposed before decomposition reaction occurs is employed, an additional specific operation for subjecting the decomposition target substance to detoxication processing is required.
Also, if the decomposition target substance in the reaction vessel, which is still in the course of decomposition, remains undecomposed when operation of the apparatus is stopped due to interruption and termination of purification processing, an additional specific operation for processing of collection and detoxication of this left decomposition target substance.
The present invention has as its object the provision of a method of decomposing pollutants that enables the above described problems to be solved, and an apparatus for the same.
According to an aspect of the present invention, there is provided a method of decomposing substances to be decomposed in which a decomposition target substance and a decomposition promoting substance having a function to decompose the decomposition target substance under irradiation with light are introduced into a decomposition area for decomposing the decomposition target substance, and those substances are contacted with each other under irradiation with light to decompose the decomposition target substance, the method comprising the steps of:
(a) introducing the decomposition promoting substance into the decomposition area;
(b) Irradiating the decomposition area with light; and
(c) introducing the decomposition target substance into the decomposition area,
wherein the steps are started in the order of the steps (a), (b) and (c), the step (a) the earliest, at the time of starting the operation of decomposing the decomposition target substance,
and the steps are stopped in the order of (c), (b) and (a), the step (c) the earliest, at the time of ending the operation of decomposing the decomposition target substance.
According to another aspect of the present invention, there is provided an apparatus for decomposing substances to be decomposed in which a decomposition target substance and a decomposition promoting substance having a function to decompose the decomposition target substance under irradiation with light are introduced into a decomposition area for decomposing the decomposition target substance, and those substances are contacted with each other under irradiation with light to decompose the decomposition target substance, comprising:
a decomposition unit comprised of the decomposition area;
a decomposition promoting substance introduction unit (d) for introducing the decomposition promoting substance into the decomposition area;
a light-irradiation unit (e) for irradiating the decomposition area with light;
a decomposition target substance introduction unit (f) for introducing the decomposition target substance into the decomposition area; and
a drive unit for driving the decomposition promoting substance introduction unit (d), the light-irradiation unit (e) and the decomposition target substance introduction unit (f) individually,
wherein the drive unit starts driving the decomposition promoting substance introduction unit (d), the light-irradiation unit (e) and the decomposition target substance introduction unit (f) in the described order at the time of starting the operation of decomposing the decomposition target substance,
and stops the operated decomposition target substance introduction unit (f), the operated light-irradiation unit and (e) the operated decomposition promoting substance introduction unit (d) in the described order at the time of ending the operation of decomposing the decomposition target substance.
According to still another aspect of the present invention, there is provided a method of decomposing substances to be decomposed in which a decomposition target substance and a decomposition promoting substance having a function to decompose the decomposition target substance under irradiation with light are introduced into a decomposition area for decomposing the decomposition target substance, and those substances are contacted with each other under irradiation with light to decompose the decomposition target substance, the method comprising the steps of:
(a) introducing the decomposition promoting substance into the decomposition area;
(b) irradiating the decomposition area with light; and
(c) introducing the decomposition target substance into the decomposition area,
wherein the steps are started in the order of the steps (a), (b) and (c), the step (a) the earliest, at the time of starting the operation of decomposing the decomposition target substance.
According to a further aspect of the present invention, there is provided a method of decomposing substances to be decomposed in which a decomposition target substance and a decomposition promoting substance having a function to decompose the decomposition target substance under irradiation with light are introduced into a decomposition area for decomposing the decomposition target substance, and those substances are contacted with each other under irradiation with light to decompose the decomposition target substance, the method comprising the steps of:
(a) introducing the decomposition promoting substance into the decomposition area;
(b) irradiating the decomposition area with light; and
(c) introducing the decomposition target substance into the decomposition area,
wherein the steps are stopped in the order of the steps (c), (b) and (a), the step (c) the earliest, at the time of stopping the operation of decomposing the decomposition target substance.
According to a further aspect of the present invention, there is provided an apparatus for decomposing substances to be decomposed in which a decomposition target substance and a decomposition promoting substance having a function to decompose the decomposition target substance under irradiation with light are introduced into a decomposition area for decomposing the decomposition target substance, and those substances are contacted with each other under irradiation with light to decompose the decomposition target substance, comprising:
a decomposition unit comprised of the decomposition area;
a decomposition promoting substance introduction unit (d) for introducing the decomposition promoting substance into the decomposition area;
a light-irradiation unit (e) for irradiating the decomposition area with light;
a decomposition target substance introduction unit (f) for introducing the decomposition target substance into the decomposition area; and
a drive unit for driving the decomposition promoting substance introduction unit (d), the light-irradiation unit (e) and the decomposition target substance introduction unit (f) individually,
wherein the drive unit starts driving the decomposition promoting substance introduction unit (d), the light-irradiation unit (e) and the decomposition target substance introduction unit (f) in the described order at the time of starting the operation of decomposing the decomposition target substance.
According to a further aspect of the present invention, there is provided an apparatus for decomposing substances to be decomposed in which a decomposition target substance and a decomposition promoting substance having a function to decompose the decomposition target substance under irradiation with light are introduced into a decomposition area for decomposing the decomposition target substance, and those substances are contacted with each other under irradiation with light to decompose the decomposition target substance, comprising:
a decomposition unit comprised of the decomposition area;
a decomposition promoting substance introduction unit (d) for introducing the decomposition promoting substance into the decomposition area;
a light-irradiation unit (e) for irradiating the decomposition area with light;
a decomposition target substance introduction unit (f) for introducing the decomposition target substance into the decomposition area; and
a drive unit for driving the decomposition promoting substance introduction unit (d), the light-irradiation unit (e) and the decomposition target substance introduction unit (f) individually,
wherein the drive unit stops the operated decomposition target substance introduction unit (f), the operated light-irradiation unit and (e) the operated decomposition promoting substance introduction unit (d) in the described order at the time of ending the operation of decomposing the decomposition target substance.